Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760596AbYARLFv (ORCPT ); Fri, 18 Jan 2008 06:05:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754708AbYARLFm (ORCPT ); Fri, 18 Jan 2008 06:05:42 -0500 Received: from twin.jikos.cz ([213.151.79.26]:51283 "EHLO twin.jikos.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754540AbYARLFl (ORCPT ); Fri, 18 Jan 2008 06:05:41 -0500 Date: Fri, 18 Jan 2008 12:04:55 +0100 (CET) From: Jiri Kosina To: Steven Rostedt cc: LKML , Linus Torvalds , Andrew Morton , Alexey Dobriyan , Kirill Korotaev Subject: Re: [PATCH] printk deadlocks if called with runqueue lock held In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1087 Lines: 29 On Thu, 17 Jan 2008, Steven Rostedt wrote: > Thinking that it was locking up on my code I went looking down the wrong > path. I finally found (after examining an NMI dump) that the lockup > happened because printk was trying to wakeup the klogd daemon, which > caused a deadlock when the try_to_wakeup code tries to grab the runqueue > lock. ... which I have documented in the printk() comment's in commit 1492192b :) > Since printks are seldom called with interrupts disabled, we can > hold off the waking of klogd if they are. We don't have access to > the runqueue locks from printk, but those locks need interrupts > disabled in order to be held. If this patch is going to be merged, you should perhaps adjust the comment introduced by the above mentioned commit, so that it reflects the new behavior. Thanks, -- Jiri Kosina -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/